The arrival of an advanced aged society causes a fear that there will be a further increase in the number of patients suffering from brain diseases such as dementia and Alzheimer's syndrome. Many people though not affected by brain diseases, experience in their daily lives such phenomena as serious forgetfulness or suffer from more frequent lapses of memory. In many cases, these phenomena would be considered a symptom of aging in the form of brain diseases.
Generally, it is believed that active oxygen species generation in living organisms participates in various disease processes. However, its relevance in brain disease has not been completely elucidated. Further, no technology has been developed that completely inhibits or controls the generation of active oxygen species. Accordingly, at present no effective and reliable preventive and therapeutic technologies exist, which are effective for the treatment and/or prevention of brain diseases.
Recently, naturally occurring plant substances having physiological activities have become the center of interest worldwide. Numerous naturally occurring plant substances have been put into practical use. Special attention has been given to buckwheat seeds, which have been used as a food source in Japan for hundreds of years. The present inventors discovered an inhibitor of lipid peroxide, a cholesterol level decreasing agent, a neutral fat levels decreasing agent and an agent for improving hyperlipemia which contains as an active ingredient an essence extracted from buckwheat husks or fractionation products thereof. A patent application directed to that invention has already been filed (Japanese Patent Application Laid-open No. Hei 10-218786).
Buckwheat is one of the most popular foods that Japanese people eat daily. In fact, buckwheat is often given to neighbors as a small house-warming gift and is a ceremonial food enjoyed on New Year's Eve. In addition, buckwheat is a popular remedy used for preventing hypertension and lowering neutral fat levels. Known components of buckwheat include, flavonoids, such as, rutin and quercetin; and polyphenols, such as, proanthocyanidine. Of these components the utilization of rutin is generally well known.
Polyphenol compounds, the secondary metabolites of plants, are well known. These compounds are present in the plant kingdom in a wide variety and in large amounts. These compounds are particularly important in the fields of pharmacy and plant chemistry since they exhibit various kinds of physiological activities. Tea polyphenols, particularly catechins, have recently become important in the field of health-care foods. These compounds are known to have various activities including, antimicrobial, antiviral, antimutational, antioxidative, anticarious, and antiallergic activities. Further, these compounds have been found to inhibit increases in blood pressure, decrease blood cholesterol levels, improve enteric bacterial flora, and exhibit deodorizing capabilities.
Research reports have been made on the components of buckwheat seed. In addition, some reports refer to the physiological activity and effect of polyphenol compounds. However, no reports have shown that buckwheat seed components have a beneficial effect in treating and improving brain function.